Temporomandibular/orofacial pain disorders (TMD) are a group of painful conditions with multiple determinants. A number of psychosocial treatments for TMD have been developed, but overall effectiveness has been limited, and the mechanisms of treatment are unknown. This proposal has two main goals: 1) to develop a highly individualized, adaptive treatment for TMD that has potential to be more effective than other psychosocial treatments; and 2) to discover the mechanisms by which psychosocial treatments work in chronic pain. Patients with TMD-related pain of at least 3 months duration (N=160) will be randomly assigned to either a Standard Conservative Treatment +Cognitive Behavioral coping skills treatment (STD+CBT), or to an Individualized Assessment and cognitive- behavioral Treatment Program (IATP) for patients with TMD pain. Treatment in IATP will be based on a very detailed functional analysis of the patient's pain experience, in context, as derived from Experience Sampling (ES). The ES procedure will be conducted via smartphone app at a rate of 4 records per day, and will be used to gather information on patients' pain, momentary cognitions, affects, and coping behaviors, for a 2-week monitoring period prior to the beginning of treatment. Therapists will use this information to develop an individual functional analysis of pain and non-pain episodes, and determine what thoughts, feelings and actions are effective for that patient at managing pain and which are not. The information will be used to help develop adaptive coping tactics in a 6-session treatment program, offering skills training tailored to specific patient needs. During-treatment ES will allow adjustment of the treatment goals and procedures, making the treatment adaptive and able to change with changing circumstances and patient needs. This experimental treatment (IATP) will be added to a standard conservative splint-based treatment for TMD pain (STD). The combination (STD+IATP) will be compared to a STD treatment supplemented with a 6 session conventional cognitive-behavioral program not based on in-vivo assessment of pain and coping. In the STD+CBT condition ES data will be collected but will not be used to inform treatment, but will control for measurement reactivity. ES data collected prior to, during, and following both treatments (out to 12 months) will allow very precise measurement of cognitions, affects, and coping skills, as they occur in patients' home environments, and how they change over time. Outcomes will include measures of pain, interference, and depressive symptoms. The study will be able to tailor treatment based on patient experiences measured in near- real time at pain episodes, allow for adaptation of treatment as it progresses, and measure the impact on outcomes of coping changes over the long-term. The results will shed light on active mechanisms of treatment for TMD and may have implications for the management of other chronic pain conditions.